Risk to Shellfish

Invasive species that affect Washington’s shellfish come in all shapes and sizes. Some, such as European green crabs and Japanese oyster drills, are visible to the naked eye. Others such as protists, bacteria, and viruses, are microscopic, making them impossible to see and hard to detect. These marine micro-invaders are pests and pathogens that can cause diseases and massive mortalities for native and commercially important shellfish. Shellfish can get sick, just like us!

One potential pathway for introduction or spread of these marine micro-invaders is the mishandling of live seafood products. Discarding empty shells or putting live or dead seafood into state waters, such as temporarily storing market-purchased seafood off a dock or beach to keep it fresh, are examples of this. Finally, even moving shellfish harvested in Washington to other places in the state can unintentionally spread harmful organisms.

Keeping shellfish in Washington healthy is important to the thousands of jobs in the shellfish industry and hundreds of thousands of recreational shellfish harvesters. Shellfish also are culturally important to tribes for food and ceremonial practices. Shellfish are important to the way of life for many in the region. Please help Safeguard Our Shellfish from “micro-invaders” and other invasive species!

Protecting Washington State Waters

When Harvesting

When harvesting oysters recreationally, remember to shuck oysters on the beach and leave the shells at the tide height where they were harvested. It’s the law and this practice prevents the accidental transfer of invasive species between beaches.

Discarding Shells

Shells from a shellfish harvest or from seafood bought at a market should be thrown in the garbage, not on the beach or in the water, to prevent the spread of micro-invaders that kill shellfish.

Storing Live Seafood

The best option is to store live seafood in the refrigerator or in a cooler or bucket with seawater. Use an aerator and storage bags filled with ice to keep the seawater cold and the seafood at a safe temperature. When done, dump the seawater in the yard so it does not go back into the marine environment. Storing shellfish in state waters may be allowed with a permit from the Washington Department of Fish and Wildlife.

Never release live or dead seafood, such as lobsters, crabs, or other shellfish, into Washington waters for any reason. While well-intentioned, this activity can introduce species or their associated micro-invaders to new environments all over the world.

Never bring prohibited, live seafood products, such as Louisiana crawfish, to Washington. These animals can multiply and become invasive and may introduce harmful diseases.


Report illegal shellfish harvests, movements, and mishandling of live seafood products to the Washington Department of Fish and Wildlife’s Enforcement.

Report observations of shellfish deaths online using this report form.

Program Highlights

The Washington Department of Fish and Wildlife Shellfish and Seaweed Health Unit works closely with the shellfish industry to regulate the movement of shellfish for commercial purposes. Department staff regularly inspect shellfish and seafood facilities, public aquariums, and research labs to ensure they are following regulations and using best practices to avoid spreading micro-invaders and other invasive species.

The department also educates the public about the risks to shellfish posed by disease and organisms and participates in research projects. Finally, the department monitors invasive pests throughout Washington’s waters and implement a range of regulations aimed at protecting waterways from organisms harmful to shellfish and the marine environment.

Import and Transfer Permits

Check out Washington Department of Fish and Wildlife’s shellfish health and cultivation permitting (transfers and imports) website.


Watch the YouTube Safeguard Our Shellfish presentation on micro-invaders presented during the 2023 Washington Invasive Species Awareness Week! A PDF of the slides from the video is also available.

To learn more about micro-invaders that negatively affect shellfish health, visit the Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish website (Bower, Fisheries and Oceans Canada).

Learn more about other invasive pests that negatively affect shellfish: